1. Now examine all the igneous rocks in your tray. Why do you think some igneous rocks show large crystals while others do not? In other words, knowing how igneous rocks form, what process would cause large crystals to form?
2. The two most important types of igneous rocks for oceanography are granite and basalt. Use your textbook to distinguish the difference physically and chemically between these two types of igneous rocks.
3. As soon as new basaltic ocean floor forms at the mid-ocean ridge, sediment begins to accumulate upon it. From this information, what conclusions could you draw about the age of the sea floor and the thickness of sediments that cover it as it moves away from a ridge?
4. One way of estimating the rate at which new seafloor is being created is to determine the age of the oldest basalt crust as shown on the following page. This rate is called the halfspreading rate. In order to get the total spreading rate you would multiply the halfspreading rate by two. Can you think of why the total spreading rate is calculated in this manner?
5. Did you get the same density using both methods? If not, hypothesize why you may have got differences and speculate of which of the two methods is the most accurate?
6. What would happen if a ‘tectonic plate' of granite collided with a ‘tectonic plate' of wood much like a convergent plate boundary?
7. How does the question from (6) relate to what happens when two plates of different density collide on earth?
Attachment:- rocks_minerals__plate_tectonics_post.pdf